The Associated Press
reported that a campaign aide stood on a bench and tried to
block the signs.

It wasn't clear why the protesters did not like Walker.
However, one video showed a heckler shouting the name of Sen.
Bernie Sanders (I-Vermont), a Democratic presidential candidate.

"You suck!" the man yelled at Walker.

Watch below:

At another point, a heckler told Walker to go back to
Wisconsin:

Walker did avoid one notable controversy during his trip to
Geno's and another prominent cheesesteak spot, Pat's King of
Steaks. In 2004, Democratic presidential nominee John Kerry
ordered Swiss cheese on his cheesesteaks instead of the customary
Cheese Whiz. Walker ordered his food with the apparently more
acceptable American cheese.